At present, full-color display is one of the objects of the development of OLED. A full-color image requires obtaining continuously adjustable colors in the range of visible wavelengths, and white light is a light that contains the three primary colors of red, green and blue in the visible light range. If a white-light OLED is combined with the well-developed microelectronic-etching color filter technology, a full-color OLED, which has an easy manufacturing process, a good reproducibility and a low cost, can be obtained.
Currently, there are many kinds of structures that can realize white light OLED, including multiple-device stacked structure, color conversion structure, single-light emitting layer structure and multi-light emitting layer structure, etc. Among these structures, the multi-light emitting layer structure is widely applied in the white light OLED due to the advantages of relatively easy process and good color stability.
FIG. 1 shows a common OLED with a multi-light emitting layer structure, which includes a cathode and an anode, as well as an electron transport layer, a second light-emitting sub-layer, an isolation layer, a first light-emitting sub-layer, a hole transport layer and the like provided in sequence between the cathode and the anode.
It may be found that, in the above OLED with the multi-light emitting layer structure, the number of device layers included is large, thus a high voltage is required to drive a/an hole/electron to a light-emitting layer, which causes a high power consumption. In addition, the complexity of the process will also be raised due to the large number of layers.
However, the above OLED with the multi-light emitting layer structure may be a white-light OLED, or it may be an OLED that emits light of other colors.